The present invention provides novel [1,2,3]-triazolo[4,5-d]pyrimidine analogues, their use as medicaments, compositions containing them and processes for their preparation.
Platelet adhesion and aggregation are initiating events in arterial thrombosis. Although the process of platelet adhesion to the sub-endothelial surface may have an important role to play in the repair of damaged vessel walls, the platelet aggregation that this initiates can precipitate acute thrombotic occlusion of vital vascular beds, leading to events with high morbidity such as myocardial infarction and unstable angina. The success of interventions used to prevent or alleviate these conditions, such as thrombolysis and platelet-mediated occlusion or re-occlusion also compromises angioplasty.
A number of converging pathways lead to platelet aggregation. Whatever the initial stimulus, the final common event is a cross-linking of platelets by binding of fibrinogen to a membrane-binding site, glycoprotein IIb/IIIa (GPIIb/IIIa). The high anti-platelet efficacy of antibodies or antagonists for GPIIb/IIIa is explained by their interference with this final common event. However, this efficacy may also explain the bleeding problems that have been observed with this class of agent. Thrombin can produce platelet aggregation largely independently of other pathways but substantial quantities of thrombin are unlikely to be present without prior activation of platelets by other mechanisms. Thrombin inhibitors such as hirudin are highly effective anti-thrombotic agents, but again may produce excessive bleeding because they function as both anti-platelet and anti-coagulant agents (The TIMI 9a Investigators (1994), Circulation 90, pp. 1624-1630; The Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIa Investigators (1994) Circulation 90, pp. 1631-30 1637; Neuhaus K. L. et. al. (1994) Circulation 90, pp. 1638-1642).
It has been found that adenosine 5xe2x80x2-diphosphate (ADP) acts as a key mediator of thrombosis. ADP-induced platelet aggregation is mediated by the P2T receptor subtype located on the platelet membrane. The P2T receptor (also known as P2YADP or P2TAC) is primarily involved in mediating platelet aggregation/activation and is a G-protein coupled receptor. The pharmacological characteristics of this receptor have been described, for example, in the references by Humphries et al., Br. J. Pharmacology, (1994), 113, 1057-1063, and Fagura et al., Br. J. Pharmacology (1998)124, 157-164. Recently it has been shown that antagonists at this receptor offer significant improvements over other anti-thrombotic agents (see J. Med Chem. (1999) 42, 213). There is a need to find P2T (P2YADP or P2TAC) antagonists as anti-thrombotic agents.
In a first aspect the invention provides a compound of formula (I): 
wherein:
R1 is OR5 or CH2R6;
R2 is alkyl C1-6 or haloalkyl C1-6;
R3 is cycloalkyl C3-6, optionally substituted by R7;
R4 is alkyl C1-6;
R5 is H or alkyl C1-6, optionally substituted by OH;
R6 is OH, N3, or NHR8;
R7 is phenyl, optionally substituted by one or more groups selected from alkyl C1-6, halogen, and OR10;
R8 is H, alkyl C1-6, or COR9;
R9 is alkyl C1-6;
R10 is alkyl C1-6;
or a pharmaceutically acceptable salt or solvate thereof, or a solvate of such a salt.
Preferably the compound of formula (I) has the following stereochemistry: 
Where R3 is 
the stereochemistry is preferably 
Suitably R1 is OH, O(CH2)2OH, CH2OH, CH2N3, CH2NH2, or CH2NHAc.
Suitably R2 is n-Pr.
Suitably R3 is cyclopropyl optionally substituted with phenyl, optionally substituted by one or more groups selected from alkyl C1-6, halogen and OR10.
Suitably R4 is methyl.
Particularly preferred compounds of the invention include:
[1S-[1xcex1,2xcex1,3xcex2,5xcex2(1S*, 2R*)]]-3-(2-Hydroxyethoxy)-5-[7-[N-methyl-(2-phenylcyclopropyl)amino]-5-(propylthio)-3H-[1,2,3]-triazolo[4,5-d]pyrimidin-3-yl]cyclopentane-1,2-diol;
[1S-[1xcex1,2xcex2,3xcex2,4xcex1(1S*, 2R*)]]4-[7-[N-Methyl-(2-phenylcyclopropyl)amino]-5-(propylthio)-3H-[1,2,3]-triazolo[4,5-d]pyrimidin-3-yl]cyclopentane-1,2,3-triol;
[1S-[1xcex1,2xcex1,3xcex2,5xcex2(1S*,2R*)]]-3-(Hydroxymethyl)-5-[7-[N-methyl-(2-phenylcyclopropyl)amino]-5-(propylthio)-3H-[1,2,3]-triazolo[4,5-d]pyrimidin-3-yl]cyclopentane-1,2-diol;
[1S-[1xcex1,2xcex2,3xcex2,4xcex1(1S*,2R*)]]-4-[7-[N-[2-(3,4-Difluorophenyl)cyclopropyl]-N-methylamino]-5-(propylthio)-3H-[1,2,3]-triazolo[4,5-d]pyrimidin-3-yl]cyclopentane-1,2,3-triol;
[1S-[1xcex1,2xcex2,3xcex2,4xcex1(1S*,2R*)]]4-[7-N-[2-(4Methoxyphenyl)cyclopropyl]-N-methylamino]-5-(propylthio)-3H-[1,2,3]-triazolo[4,5-d]pyrimidin-3-yl]cyclopentane-1,2,3 -triol;
[1S-[1xcex1,2xcex1,3xcex2,5xcex2(1S*,2R*)]]-3-Azidomethyl-5-[7-[N-methyl-(2-phenylcyclopropyl)amino]-5-(propylthio)-3H-[1,2,3]-triazolo[4,5-d]pyrimidin-3-yl]cyclopentane-1,2-diol;
[1S-[1xcex1,2xcex1,3xcex2,5xcex2(1S*,2R*)]]-3-Aminomethyl-5-[7-[N-methyl-(2-phenylcyclopropyl)amino]-5-(propylthio)-3H-[1,2,3]-triazolo[4,5-d]pyrimidin-3-yl]cyclopentane-1,2-diol;
[1R-[1xcex1,2xcex1,3xcex2,4xcex1(1R*,2S*)]]-N-[[2,3-Dihydroxy4-[7-[N-methyl-(2-phenylcyclopropyl)amino]-5-(propylthio)-3H-[1,2,3]-triazolo[4,5-d]pyrimidin-3-yl]cyclopentyl]methyl]acetamide;
or a pharmaceutically acceptable salt or solvate thereof, or a solvate of such a salt.
According to the invention there is further provided a process for the preparation of a compound of formula (I) which comprises:
a. For compounds of formula (I) where R1 is O(CH2)2OH, the reaction of a compound of formula(II) 
where R2, R3 and R4 are defined in formula (I). P and Pxe2x80x2 are protecting groups, for example CMe2, with 2-(2-bromoethoxy)-2H-tetrahydropyran, in the presence of dimethylsulphoxide and a phase transfer catalyst, such as a tetra-alkylammonium halide, preferably tetra-butylammonium bromide, and aqueous sodium hydroxide, in the presence of a water-immiscible organic solvent, preferably toluene, at a temperature of between about 50 and about 120xc2x0 C., and optionally thereafter removing any protecting groups.
Protecting groups can be added and removed using known reaction conditions. The use of protecting groups is fully described in xe2x80x98Protective Groups in Organic Chemistryxe2x80x99, edited by J W F McOmie, Plenum Press (1973), and xe2x80x98Protective Groups in Organic Synthesisxe2x80x99, 2nd edition, T W Greene and P G M Wutz, Wiley-Interscience (1991).
Tetrahydropyranyl groups can be removed by the use of an acid, for example, trifluoroacetic acid, in water or aqueous acetonitrile, at a temperature between about 20 and about 50xc2x0 C.
A compound of formula (II) can be prepared by reacting a compound of formula (III) 
where P, Pxe2x80x2, R2 are defined above, with R3R4NH, in the presence of a base, preferably N,N-di-isopropylethylamine, in an inert ethereal solvent, preferably diethyl ether or tetrahydrofuran or a chlorocarbon solvent, preferably dichloromethane, at a temperature of between about 20 and about 50xc2x0 C.
Where R3R4NH is 
and R7 is phenyl, the compound may be prepared as described by C. Kaiser et al, J. Org. Chem., 1962, 27, 768-773, using (1R-trans)-2-phenylcyclopropanamine, [R-(R*,R*)]-2,3-dihydroxybutanedioate (1:1) (prepared as described by L. A. Mitscher et al, J. Med. Chem., 1986, 29, 2044).
Where R3R4NH is 
such compounds can be prepared by acylation of 
(prepared as described in International Patent Application WO 9905143) with acetic anhydride and potassium carbonate in tetrahydrofuran, at a temperature of between about 20 and about 50xc2x0 C. The product of this reaction can be methylated with sodium hydride and methyl iodide in tetrahydrofuran, at a temperature of between about 20 and about 50xc2x0 C., followed by deacylation with aqueous hydrochloric acid, at a temperature of between about 20 and about 100xc2x0 C.
A compound of formula (III) can be prepared by diazotising a compound of formula (IV) 
where P, Pxe2x80x2 and R2 are defined above, with an alkyl nitrite, preferably iso-amylnitrite, in an inert dipolar aprotic solvent, preferably acetonitrile, at a temperature between about 50 and is about 100xc2x0 C.
A compound of formula (IV) can be prepared by reducing a compound of formula (V), 
where P, Pxe2x80x2 and R2 are defined above, using a metal, preferably iron powder, in the presence of an acid, preferably acetic acid, at a temperature between about 20 and about 50xc2x0 C.
A compound of formula (V) can be prepared by reacting a compound of formula (VI), 
where P and Pxe2x80x2 are defined above, with a compound of formula (VII): 
where R2 is defined above, in the presence of a base, preferably N,N-di-isopropylethylamine, in an inert ethereal solvent, preferably tetrahydrofuran, at a temperature between about 20 and about 50xc2x0 C.
Where R2 is n-Pr, the compound of formula (VII) can be prepared as described in International Patent Application WO 9703084.
A compound of formula (VI) can be prepared by reacting a compound of formula (VIII), 
with a ketal or acetal, preferably 2,2-dimethoxypropane, in acetone as solvent, in the presence of an acid, preferably p-toluenesulphonic acid, at a temperature of between about 20 and about 50xc2x0 C., followed by hydrolysis and decarboxylation of the protected iminodiester under aqueous conditions, preferably in water, at a temperature of between about 100 and about 120xc2x0 C.
A compound of formula (VIII) can be prepared by dihydroxylating a compound of formula (IX), 
using osmium tetroxide, in the presence of an oxidising agent, preferably N-methylmorpholine-N-oxide, under aqueous conditions, preferably in aqueous tetrahydrofuran, at a temperature between about 20 and about 50xc2x0 C.
A compound of formula (IX) can be prepared by reacting a compound of formula (X): 
with a protected amine, preferably imidodicarbonic acid bis-(1,1-dimethylethyl)ester, in the presence of a base, preferably sodium hydride, and an organometallic catalyst, preferably tetrakis(triphenylphosphine)palladium(0), in an inert ethereal solvent, preferably tetrahydrofuran, at a temperature between about 20 and about 100xc2x0 C.
b. For compounds of formula (I) where R1 is OH, reacting a compound of formula (XI): 
where P is a protecting group and R2 and R3 are defined above, with a base, preferably sodium hydride, and an alkylating agent, preferably methyl iodide, in an inert dipolar aprotic solvent preferably N,N-dimethylformamide, at a temperature of between about 20 and about 50xc2x0 C., and optionally thereafter removing any protecting groups
Protecting groups include trialkylsilyl groups, preferably the t-butyldimethylsilyl group. This can be removed by reaction with a tetraalkylammonium fluoride, preferably tetrabutylammonium fluoride, under aqueous conditions, preferably aqueous tetrahydrofuran, at a temperature between about 20 and about 50xc2x0 C.
A compound of formula (XI) can be made by reacting a compound of formula (XII): 
where R2 and R3 are defined above with a trialkylsilylhalide, preferably t-butyldimethylsilylchloride, in the presence of imidazole, in an inert dipolar aprotic solvent, preferably N,N-dimethylformamide, at a temperature between about 20 and about 50xc2x0 C.
A compound of formula (XII) can be made by reacting a compound of formula (XIII): 
where R2 is as defined in formula (I), with an amine R3NH2, in the presence of a base, preferably N,N-di-isopropylethylamine, in an inert ethereal solvent, preferably diethyl ether or tetrahydrofuran, at a temperature between about 20 and about 50xc2x0 C.
Where R3NH2 is (1R-trans)-2-phenylcyclopropanamine, (1R-trans)-2-phenylcyclopropanamine, [R-(R*,R*)]-2,3-dihydroxybutanedioate (1:1) it may be prepared as described by L. A. Mitscher et al, J. Med. Chem., 1986, 29, 2044.
A compound of formula (XIII) can be made by reducing a compound of formula (XIV), 
where R2 is defined above, in the presence of a metal, preferably iron powder, and an acid, preferably acetic acid, at a temperature between about 20 and about 50xc2x0 C., followed by diazotisation of the aminopyrimidine using an alkylnitrite, preferably iso-amylnitrite, in an inert dipolar aprotic solvent, preferably acetonitrile, at a temperature between about 50 and about 100xc2x0 C.
A compound of formula (XIV) can be prepared by reacting a compound of formula (VII) with a compound of formula (XV) 
in the presence of a base, preferably triethylamine or N,N-di-isopropylethylamine, in an inert ethereal solvent, preferably tetrahydrofuran, at a temperature between about 20 and about 100xc2x0 C.
Compounds of formula (XV) can be prepared by the hydrolysis and decarboxylation of a compound of formula (VIII) using the methods described in step a.
c. For compounds of formula (I) where R1 is CH2OH the reaction of a compound of formula (XVI) 
where R2 is defined in formula (I), P and Pxe2x80x2 are protecting groups, with R3R4NH and a base, preferably N,N-di-isopropylethylamine, in a chlorocarbon solvent, preferably dichloromethane, at a temperature of between about 20 and about 50xc2x0 C., and optionally thereafter removing any protecting groups.
The preparation of R3R4NH is described above.
Where P and Pxe2x80x2 are CMe2, the protecting groups can be removed using an acid under aqueous conditions, preferably using aqueous hydrochloric acid or aqueous trifluoroacetic acid in an alcoholic solvent, preferably methanol at a temperature between about 20 and about 50xc2x0 C.
The preparation of a compound of formula (XVI), where P and Pxe2x80x2 are CMe2, is described in International Patent Application WO 9703084.
d. For compounds of formula (I) where R1 is CH2N3, the reaction of a compound of formula (XVII) 
where R2, R3 and R4 are defined in formula (I), and P and Pxe2x80x2 are protecting groups, with an alkali metal azide, preferably sodium azide, in an inert chlorocarbon solvent, preferably dichloromethane, at a temperature between about 20 and about 50xc2x0 C., and optionally thereafter removing any protecting groups.
A compound of formula (XVII) can be made by reaction of a compound of formula (XVIII) 
where R2, R3 and R4 are defined in formula (I), P and Pxe2x80x2 are protecting groups, with an iodinating agent, preferably methyltriphenoxyphosphonium iodide, in an inert chlorocarbon solvent, preferably dichloromethane, at a temperature between about 20 and about 50xc2x0 C.
Compound (XVIII) can be prepared using the methods described in steps a-c.
e. For compounds of formula (I) where R1 is CH2NH2, reduction of a compound of formula (I) where R1 is CH2N3 (synthesised as described in step d), with hydrogen, in the presence of a transition metal catalyst, preferably 10% palladium on carbon, in an inert alcoholic solvent, preferably ethanol, at a temperature between about 20 and about 50xc2x0 C., and optionally thereafter removing any protecting groups.
f. For compounds of formula (I) where R1 is CH2NHCOR9, where R9 is defined above, acylation of a compound of formula (I) where R1 is CH2NH2 (synthesised as described in step e), with an acylating agent, preferably an acid anhydride (R9CO)2O, in the presence of a base, preferably N,N-diisopropylethylamine, in an inert chlorocarbon solvent, preferably dichloromethane, at a temperature between about 20 and about 50xc2x0 C., followed by treatment with an alkali metal alkoxide, preferably sodium methoxide, in an alcoholic solvent, preferably methanol, at a temperature between about 20 and about 50xc2x0 C., and optionally thereafter removing any protecting groups.
Compounds of formulae (II), (XVII), and (XVIII) form a further aspect of the invention.
Salts of the compounds of formula (I) may be formed by reacting the free base, or a salt or a derivative thereof, with one or more equivalents of the appropriate acid (for example a hydrohalic (especially HCl), sulphuric, oxalic or phosphoric acid). The reaction may be carried out in a solvent or medium in which the salt is insoluble or in a solvent in which the salt is soluble, e.g. water, ethanol, tetrahydrofuran or diethyl ether, which may be removed in vacuo, or by freeze drying. The reaction may also be a metathetical process or it may be carried out on an ion exchange resin. The non-toxic physiologically acceptable salts are preferred, although other salts may be useful, e.g. in isolating or purifying the product.
The compounds of the invention act as P2T (P2YADP or P2TAC) receptor antagonists. Accordingly, the compounds are useful in therapy, including combination therapy, particularly they are indicated for use as: inhibitors of platelet activation, aggregation and degranulation, promoters of platelet disaggregation, anti-thrombotic agents or in the treatment or prophylaxis of unstable angina, coronary revascularisation procedures including angioplasty (PTCA), myocardial infarction, perithrombolysis, primary arterial thrombotic complications of atherosclerosis such as thrombotic or embolic stroke, transient ischaemic attacks, peripheral vascular disease, myocardial infarction with or without thrombolysis, arterial complications due to interventions in atherosclerotic disease such as angioplasty, endarterectomy, stent placement, coronary and other vascular graft surgery, thrombotic complications of surgical or mechanical damage such as tissue salvage following accidental or surgical trauma, reconstructive surgery including skin and muscle flaps, conditions with a diffuse thrombotic/platelet consumption component such as disseminated intravascular coagulation, thrombotic thrombocytopaenic purpura, haemolytic uraemic syndrome, thrombotic complications of septicaemia, adult respiratory distress syndrome, anti-phospholipid syndrome, heparin-induced thrombocytopaenia and pre-eclampsia/eclampsia, or venous thrombosis such as deep vein thrombosis, venoocclusive disease, haematological conditions such as myeloproliferative disease, including thrombocythaemia, sickle cell disease; or in the prevention of mechanically-induced platelet activation in vivo, such as cardio-pulmonary bypass and extracorporeal membrane oxygenation (prevention of microthromboembolism), mechanically-induced platelet activation in vitro, such as use in the preservation of blood products, e.g. platelet concentrates, or shunt occlusion such as in renal dialysis and plasmapheresis, thrombosis secondary to vascular damage/inflammation such as vasculitis, arteritis, glomerulonephritis, inflammatory bowel disease and organ graft rejection, conditions such as migraine, Raynaud""s phenomenon, conditions in which platelets can contribute to the underlying inflammatory disease process in the vascular wall such as atheromatous plaque formation/progression, stenosis/restenosis and in other inflammatory conditions such as asthma, in which platelets and platelet-derived factors are implicated in the immunological disease process. Further indications include treatment of CNS disorders and prevention of the growth and spread of tumours.
According to the invention there is further provided the use of a compound according to the invention as an active ingredient in the manufacture of a medicament for use in the treatment or prevention of the above disorders. In particular the compounds of the invention are useful for treating myocardial infarction, thrombotic stroke, transient ischaemic attacks, peripheral vascular disease and stable and unstable angina, especially unstable angina. The invention also provides a method of treatment or prevention of the above disorders which comprises administering to a person suffering from or susceptible to such a disorder a therapeutically effective amount of a compound according to the invention.
The compounds may be administered topically, e.g. to the lung and/or the airways, in the form of solutions, suspensions, HFA aerosols and dry powder formulations; or systemically, e.g. by oral administration in the form of tablets, pills, capsules, syrups, powders or granules, or by parenteral administration in the form of sterile parenteral solutions or suspensions, by subcutaneous administration, or by rectal administration in the form of suppositories or transdermally.
The compounds of the invention may be administered on their own or as a pharmaceutical composition comprising the compound of the invention in combination with a pharmaceutically acceptable diluent, adjuvant or carrier. Particularly preferred are compositions not containing material capable of causing an adverse, e.g. an allergic, reaction.
Dry powder formulations and pressurised HFA aerosols of the compounds of the invention may be administered by oral or nasal inhalation. For inhalation the compound is desirably finely divided. The compounds of the invention may also be administered by means of a dry powder inhaler. The inhaler may be a single or a multi dose inhaler, and may be a breath actuated dry powder inhaler.
One possibility is to mix the finely divided compound with a carrier substance, e.g. a mono-, di- or polysaccharide, a sugar alcohol or another polyol. Suitable carriers include sugars and starch. Alternatively the finely divided compound may be coated by another substance. The powder mixture may also be dispensed into hard gelatine capsules, each containing the desired dose of the active compound.
Another possibility is to process the finely divided powder into spheres, which break up during the inhalation procedure. This spheronized powder may be filled into the drug reservoir of a multidose inhaler, e.g. that known as the Turbuhaler(copyright) in which a dosing unit meters the desired dose which is then inhaled by the person. With this system the active compound with or without a carrier substance is delivered to the person.
The pharmaceutical composition comprising the compound of the invention may conveniently be tablets, pills, capsules, syrups, powders or granules for oral administration; sterile parenteral or subcutaneous solutions, suspensions for parenteral administration or suppositories for rectal administration.
For oral administration the active compound may be admixed with an adjuvant or a carrier, e.g. lactose, saccharose, sorbitol, mannitol, starches such as potato starch, corn starch or amylopectin, cellulose derivatives, a binder such as gelatine or polyvinylpyrrolidone, and a lubricant such as magnesium stearate, calcium stearate, polyethylene glycol, waxes, paraffin, and the like, and then compressed into tablets. If coated tablets are required, the cores, prepared as described above, may be coated with a concentrated sugar solution, which may contain e.g. gum arabic, gelatine, talcum, titanium dioxide, and the like. Alternatively, the tablet may be coated with a suitable polymer dissolved either in a readily volatile organic solvent or an aqueous solvent.
For the preparation of soft gelatine capsules, the compound may be admixed with e.g. a vegetable oil or polyethylene glycol. Hard gelatine capsules may contain granules of the compound using either the above mentioned excipients for tablets, e.g. lactose, saccharose, sorbitol, mannitol, starches, cellulose derivatives or gelatine. Also liquid or semisolid formulations of the drug may be filled into hard gelatine capsules.
Liquid preparations for oral application may be in the form of syrups or suspensions, for example solutions containing the compound, the balance being sugar and a mixture of ethanol, water, glycerol and propylene glycol. Optionally such liquid preparations may contain colouring agents, flavouring agents, saccharine and carboxymethylcellulose as a thickening agent or other excipients known to those skilled in art.